Isn't security theater exactly the thing that's needed to deter threats? When you see guards that look like Navy Seals, it is a pretty strong deterrant.
Regular datacenters don't seem to be having major problems with technicals full of insurgents stealing hard disks, but maybe I'm just out of the loop.
No? A cursory reconnaissance (e.g. "I'm a potential customer and I'd like a tour") will usually show that sort of theatre for what it is.
Is physical attack a common method to breach a datacenter? Sure you need some physical security and auditing but I would imagine the main threat is online.
Depends on your threat model.
(Ie any serious attacker will look past the theatre.)
Deterrent of what? Did someone ever hold a datacenter hostage?